Perry took a shot at Rand first, apparently. This article reads like a rebuttal..
then they are both wasting oxygen
Correct. But, you need to realize that this is a battle between the NeoCons and Rand Paul. Perry's shot at Paul was a NeoCon shot.
This battle broke out spring 2013 when Paul(on the Senate Foreign Relations Committee) joined the two antiwar dems and voted against arming the Syrian Rebels. Then those three were joined by isolationist Mike Lee to introduce legislation opposing the arming of the rebels.
After that, it was the NeoCons who fired the first shot at Paul. They published that story about Paul's campaign aide being a NeoConfederate racist, which would imply that Paul is a racist.
Rand Paul responded by attacking Liz Cheney running for the Wyoming senate seat. And the battle has continued since. Perry's shot is just the latest.
Paul's campaign strategy is to run against the NeoCons, and because of Iraq and Afghanistan he is getting traction, he has the highest poll numbers. And most recently, many of the NeoCons(especially Cheney) have gone on TV calling for the re-invasion of Iraq and Paul has used that as ammo.
Hillary is watching this. She has hired the prominent NeoCon Fred Kagan has an advisor. No doubt if Paul gets the GOP nomination she will run heavy as an interventionist hawk. Like Joe Lieberman.